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ETHYL BENZENE

14*

action may be concentrated by fractional distillation, as in the
case of hydriodic acid (p. 113), and used in the preparation of
bromotoluene (p. 167).    It boils at 126° at the normal pressure/
has a sp.gr. of 1-49, and contains about 47 per cent, of HBr!
See Appendix•, p. 271.

PREPARATION 47.

Ethyl Benzene, CGH5.C,H5

Fittig, Annalen, 1864, 131, 303.
60 grms. bromobenzene.
52     „      ethyl bromide (see p. 54).
26'5 „      sodium.

A quantity of ether, which has been freed from alcohol by
distilling over caustic potash, and dried over calcium chloride
and sodium (see p. 61), is poured into a round flask (i litre).
The amount of ether should be about twice the volume of the
mixed phenyl and ethyl bromides. The sodium, cut into thin
slices with the sodium knife, or squeezed into fine wire, is added
to the ether, and when all evolution of hydrogen has ceased,
the flask is attached to an upright condenser and immersed in
a vessel of ice-water. The mixture of bromobenzene and ethyl
bromide, both carefully dehydrated, is poured into the flask.
The reaction is allowed to commence spontaneously, the fact
being indicated by the appearance of the sodium, which be-
comes darker in colour and sinks to the bottom of the vessel.
Although the flask is allowed to remain in the outer vessel, and
is cooled by water and ice, the heat evolved often causes the
ether to boil. The flask is therefore not removed until the re-
action is over. It is convenient to leave it over night. The
liquid is then decanted from the sodium bromide, which has a
blue colour, into a distilling flask, and rinsed out once or twice
with ether, The ether is removed on the water-bath, a bit of
porous pot being added, and the residue is fractionated with a
fractionating column. The portion boiling at 132—135° is
collected separately. Yield 20—25 grams.

CcH6Br + C2H6Br + 2Na = C0H6.C2H6 + 2NaBr.

Properties.—Colourless liquid; b. p. 134°
22'5°.    See Appendix, p. 273,

sp. gr. 0-8664 at